1. Field of the Invention
The present invention relates to a mechanized tent. In particular, it relates to a mechanized tent having a frame and a collectable tarp attached to the frame which can be raised and lowered over pallets of produce or the like, particularly useful for fumigation of produce, e.g. imported products.
2. Information Disclosure Statement
Once fumigated, produce has a shelf life of at most ten days to two weeks. It is therefore desirable to fumigate the produce close to the place where it will be ultimately sold. For imported produce, this place is typically inside a dock building or warehouse located at a port of entry. Pallets of the produce are unloaded from a ship and placed or staged on the floor of the dock building.
Known methods of fumigating produce involve covering the pallets of produce with a polyethylene or plastic impregnated tarpaulin. and then introducing a gas, e.g., methyl bromide, under the tarp to kill live insect infestations. Workers climb on top of the pallets or use poles to pull the tarp over a group of pallets. Because it is necessary for the gas to circulate freely on all sides and the top of the pallets, the tarp cannot lay flat on the top of the pallets. The United States Department of Agriculture requires that a space of about two feet be provided on the top of the pallets, and at least two feet on their sides to allow room for the placement of fans to facilitate the circulation of the fumigation gas. The fans may be tied down with rope to prevent them from moving. Several hoses for introducing the gas is secured to the top of selected fans. The volume of space under the tarp, i.e., the total cubic feet, determines how many fans and point;s of introduction are required.
One method for maintaining the required space on the top of the pallets is to erect wood frames in the shape of a xe2x80x9cTxe2x80x9d or an xe2x80x9cAxe2x80x9d at each corner and attach rope between each xe2x80x9cTxe2x80x9d or an xe2x80x9cAxe2x80x9d to create a web of support for the tarp. The side space is maintained by draping the tarp outward as it contacts the floor of the dock building and securing it in that position by placing flexible vinyl tubes (approximately 6xe2x80x3 in diameter and 4xe2x80x2 long) filled with sand on top of the edge of the tarp. At least 2 feet of excess tarp remains beyond the xe2x80x98sand tubesxe2x80x99.
The steps involved in pulling the tarp over the pallets, setting up the fans, attaching the introduction hoses to the fans, handling hundreds of tubes of sand, and dismantling and storing all of the above equipment, and repeating the process upon completion, require many labor intensive hours.
Improvements to the conventional method of fumigating produce include permanently suspending the tarpaulin from an. overhead frame and lowering the frame over the pallets as needed. Such a frame may be made from welded trusses to form a disassemblable one piece unit of varying dimensions. The typical frame size may be 50 feet long by 250 feet wide, but may be larger or smaller depending upon the spacing between support columns in the dock building. To the underside of the frame a tarpaulin is attached which has been manufactured with grammets, i.e., tabs and eyelets, specific to the frame it hangs from.
The frame may be raised and lowered by a system of cables and pulleys located above the unit which are attached to exposed barjoists on the underside of the roof of the dock building. The cables are connected to hand-operated or motor-operated winchs mounted on the support columns in the dock building. Workers simultaneously crank the winches to lower or raise the frame to a height above the pallets that allows the required 2 feet of space between the tarp and pallets of produce.
A typical tent may be lifted by twelve or more active pickup points. Between each of these points two counterweight sandbags are deployed to offset the self-weight of the frame and the polyethylene enclosure. Each truss section of the frame spans approximately fifty feet with two mid-point sandbags. These tend to become hung up from friction and pull at an angle to prevent the sandbag from lowering onto the polyethylene enclosure as it is elevated.
A difficult and time-consuming job associated with operating such a system is gathering up the tarp which overhangs from the sides of the frame before the frame is raised. This is necessary because the typical dock building height of about twenty-two feet is limited to about eighteen feet by overhead piping, electrical conduits, etc. When the support frame is raised to the maximum height permitted by these obstructions the tarp hangs down low enough to catch the tops of forklift trucks as they move the pallets of produce in and out of the tent area.
One known way of gathering up the tarp on the sides is to run horizontal plastic pipes through double-thickness portions of the tent walls which form pockets. These pockets can be located at approximately one-third and two-thirds of the wall height and are tied up to the top framing with rope every ten feet or so. Pulled ropes raise the pockets and thus gather the sides of the tent. This method is also time-consuming, however, because it requires numerous tie-up procedures in order to completely raise the tent, e.g., usually at ten to twenty foot intervals around the tent perimeter.
U.S. Pat. No. 5,641,463 utilizes many of the aforementioned improved technique features and additionally incorporates unique features which are more fully discussed in conjunction with some of the drawings described below.
Notwithstanding the above prior art, there is no teaching which anticipates or renders the present invention obvious. Thus, it is neither taught nor suggested to use a system with a ceiling-mounted suspended frame with a fumigation tarp position atop the support frame in a sealed fashion. Likewise, the prior art is deficient in teachings related to cooperating clews or other present invention features, as more fully developed below.
It is an object of the present invention to provide a large mechanized fumigation tent which incorporates the height of the supporting frame within the tarp structure to eliminate the extra space otherwise needed when the support structure is stacked above the gathered, stored tarp.
It is another object of the present invention to decrease the total weight needed for an efficiently operated fumigation tent.
It is also an object of the present invention to provide a fumigation tent which does not require permanent water storage tanks, related plumbing or the otherwise necessary space which would be occupied by permanent water storage facilities.
It is yet another object of the present invention to provide a large fumigation tent for fumigating produce, logs, textiles, wood products, and other forms of potentially infested imports which can be quickly, conveniently and freely raised and lowered over pallets of the produce.
It is also an object of the present invention to provide a fumigation tent that does not interfere with the operation of forklift trucks as they move pallets of the produce in and out of a tent area and that does not require extensive tie-up procedures to accomplish this.
Another object of the present invention is to provide a fumigation tent which can be raised from a single remote location so that personnel need not be near the tent area after. fumigation is complete since exposure to residual gas, which may not have been evacuated from some pallet areas, is possible and can be harmful.
It is yet another object of the present invention to provide for alternative mechanisms for first lifting side curtains of the tarp and then lifting the entire structure and, conversely, lowering the entire structure and then the side curtains of the tarp.
A further object of the present invention to provide a system which seals the tent to the floor of the dock building and which can be easily raised with tent.
The present invention provides a fumigation tent which includes a frame suspended from a structure by support cables, the frame having an underside; a tarp adapted to be mounted to the top side of the frame, the tarp hanging from the frame defining a tent having a top and side curtains having a lower periphery that defines a bottom perimeter; means for connecting and sealing the top of the tarp to the frame; a first plurality of cables for raising and lowering the side curtains and being connected to the side curtains and to means for raising and lowering the first plurality of cables; a second plurality of cables for raising and lowering the frame and being connected to the frame and to means for raising and lowering the second plurality of cables.
The present invention also provides a system for sealing a bottom perimeter of a lower periphery of side curtains of a tent to a floor, which includes at. least one flexible hose mounted along the bottom perimeter for attachment to an external water supply.
The present invention further provides for attachment of the winch cables to clew plates which in turn are attached to winches by winch chains. There is at least one master clew for harmonizing the movement of the first plurality of cables and at least one curtain clew for harmonizing the movement of the second plurality of cables. Preferably, the winches are motorized and can be operated by remote control. (This provides an important safety advantage, because personnel do not have to be near the tent while it is being raised. Therefore, personnel can avoid being exposed to any lingering fumigation gas which is hazardous.) It is also preferable that hand winches with cables be located near the motorized winches, so that they can be attached to the clew plates to provide emergency back up in case electrical problems occur.
Other advantages and characteristics of the present invention will become apparent in view of the description and accompanying drawings that follow.